-9x2 +17x -8 = 0
ax2 bx c = 0
a = -9
b = 17
c = -8
Δ = b2-4ac
Δ = 17² - (4 * -9 * -8)
Δ = 289 - (4*72)
Δ = 289 - (288)
Δ = 1 Δ > 0
-9x2+17x-8=0
x = -b ∓ √Δ 2a
x' = -17 - √1 2*-9 = -17 - 1.0 -18 = -18.0 -18 = 1.0
x" = -17 + √1 2*-9 = -17 + 1.0 -18 = -16.0 -18 = 0.888888888889
x' = 81.0
x" = 72.0
S = {x ∈ R / x' = 81.0, x" = 72.0 }